Abstract: The present invention relates to a knallgas bacterium or acetogenic bacterium expressing a 2-hydroxyisobutyryl-coenzyme A mutase, a method for the production of 2-hydroxyisobutyric acid, comprising contacting in an aqueous medium the knallgas bacterium or acetogenic with a gas mixture comprising hydrogen and carbon dioxide and the use of the knallgas bacterium or acetogenic bacterium for the production of 2-hydroxyisobutyric acid.

Abstract: Provided is a composition containing: an isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 4; and/or a heterodimeric enzyme containing: the isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 4; and an isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 2. Also provided is a process for producing a 2-hydroxy-2-methyl carboxylic acid or a salt or ester thereof, wherein the process involves: contacting a 3-hydroxy carboxylic acid or a salt or ester thereof with the above-mentioned composition to produce the 2-hydroxy-2-methyl carboxylic acid or the salt or ester thereof.

Abstract: Provided is a composition containing: an isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 4; and/or a heterodimeric enzyme containing: the isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 4; and an isolated and purified polypeptide containing the amino acid sequence of SEQ ID NO: 2. Also provided is a process for producing a 2-hydroxy-2-methyl carboxylic acid or a salt or ester thereof, wherein the process involves: contacting a 3-hydroxy carboxylic acid or a salt or ester thereof with the above-mentioned composition to produce the 2-hydroxy-2-methyl carboxylic acid or the salt or ester thereof.

Abstract: The present invention relates to a method for the enzymatic production of 2-hydroxy-2-methyl carboxylic acids from 3-hydroxy carboxylic acids, where a 3-hydroxy carboxylic acid is produced in an aqueous reaction solution and/or is added to this reaction solution and is incubated. The aqueous reaction solution comprises a unit having 3-hydroxy-carboxylate-CoA mutase activity which has both 3-hydroxy-carbonyl-CoA ester-producing and 3-hydroxy-carbonyl-CoA ester-isomerizing activity and converts the 3-hydroxy carboxylic acid into the corresponding 2-hydroxy-2-methyl carboxylic acid which is isolated as acid or in the form of its salts. In a preferred embodiment, the unit having 3-hydroxy-carboxylate-CoA mutase activity is a unit which includes an isolated cobalamin-dependent mutase and where appropriate a 3-hydroxy-carbonyl-CoA ester-producing enzyme or enzyme system or a microorganism including them.

Abstract: The present invention relates to a method for the enzymatic production of 2-hydroxy-2-methyl carboxylic acids from 3-hydroxy carboxylic acids, where a 3-hydroxy carboxylic acid is produced in an aqueous reaction solution and/or is added to this reaction solution and is incubated. The aqueous reaction solution comprises a unit having 3-hydroxy-carboxylate-CoA mutase activity which has both 3-hydroxy-carbonyl-CoA ester-producing and 3-hydroxy-carbonyl-CoA ester-isomerizing activity and converts the 3-hydroxy carboxylic acid into the corresponding 2-hydroxy-2-methyl carboxylic acid which is isolated as acid or in the form of its salts. In a preferred embodiment, the unit having 3-hydroxy-carboxylate-CoA mutase activity is a unit which includes an isolated cobalamin-dependent mutase and where appropriate a 3-hydroxy-carbonyl-CoA ester-producing enzyme or enzyme system or a microorganism including them.